1. Field of the Invention
The present invention relates to a digital audio signal recording method suitably applied to the case such that an audio signal is recorded on an audio track of a motion picture film in a digital fashion.
2. Description of the Related Art
In motion picture films, an analog audio signal of about two channels is recorded on a so-called sound track which is formed in the vicinity of a video recording portion.
According to the recent progress in digital audio technologies, it is known that an audio signal is converted into digital data and then recorded on a recording medium such as a magnetic tape or the like. Also in the motion pictures, it is requested that an audio signal can be recorded on a motion picture film in the form of a digital signal.
In the case of the motion picture film, however, the sound track on which the analog audio signal is recorded cannot be substantially removed from such a standpoint as to maintain a compatibility with existing film projection apparatus. Therefore, a new track on which digital audio data can be recorded must be prepared in other portion than the sound track.
U.S. Pat. No. 4,600,280 describes a technique in which a digital audio signal is recorded on a motion picture film together with a conventional sound track. Also, U.S. Pat. No. 5,101,397 describes a technique in which an audio signal is recorded in the form of digital audio signal. Furthermore, U.S. Pat. No. 4,461,552 describes a technique in which an audio signal is encoded according to the pulse-code-modulation (PCM) system and then optically recorded on a film. However, the above-mentioned prior arts all fail to disclose an arrangement in which words forming a digital audio signal are properly arranged on a film or addition and arrangement of an error detection and/or error correction for avoiding data error.